CN117512429B - LC1 valve casting method - Google Patents
LC1 valve casting method Download PDFInfo
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- CN117512429B CN117512429B CN202410017716.6A CN202410017716A CN117512429B CN 117512429 B CN117512429 B CN 117512429B CN 202410017716 A CN202410017716 A CN 202410017716A CN 117512429 B CN117512429 B CN 117512429B
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- 238000005266 casting Methods 0.000 title claims abstract description 80
- 238000000034 method Methods 0.000 title claims abstract description 54
- 238000010438 heat treatment Methods 0.000 claims abstract description 36
- 238000005496 tempering Methods 0.000 claims abstract description 24
- 238000010791 quenching Methods 0.000 claims abstract description 23
- 230000000171 quenching effect Effects 0.000 claims abstract description 23
- 238000003723 Smelting Methods 0.000 claims abstract description 19
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000000126 substance Substances 0.000 claims abstract description 15
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 9
- 239000004576 sand Substances 0.000 claims abstract description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 7
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 7
- 238000005520 cutting process Methods 0.000 claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 claims abstract description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 7
- 239000011574 phosphorus Substances 0.000 claims abstract description 7
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 7
- 239000011593 sulfur Substances 0.000 claims abstract description 7
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000005422 blasting Methods 0.000 claims abstract description 6
- 238000004140 cleaning Methods 0.000 claims abstract description 6
- 238000010891 electric arc Methods 0.000 claims abstract description 6
- 238000007689 inspection Methods 0.000 claims abstract description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 6
- 239000011733 molybdenum Substances 0.000 claims abstract description 6
- 239000003973 paint Substances 0.000 claims abstract description 6
- 238000005498 polishing Methods 0.000 claims abstract description 6
- 238000007670 refining Methods 0.000 claims abstract description 6
- 230000001680 brushing effect Effects 0.000 claims abstract description 5
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 5
- 239000011572 manganese Substances 0.000 claims abstract description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 4
- 239000010703 silicon Substances 0.000 claims abstract description 4
- 229910000831 Steel Inorganic materials 0.000 claims description 52
- 239000010959 steel Substances 0.000 claims description 52
- 238000005070 sampling Methods 0.000 claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 28
- 238000001816 cooling Methods 0.000 claims description 16
- 238000004321 preservation Methods 0.000 claims description 14
- 239000000463 material Substances 0.000 description 9
- XACAZEWCMFHVBX-UHFFFAOYSA-N [C].[Mo] Chemical compound [C].[Mo] XACAZEWCMFHVBX-UHFFFAOYSA-N 0.000 description 5
- 239000013078 crystal Substances 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 3
- 239000011162 core material Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/10—Devices for withdrawing samples in the liquid or fluent state
- G01N1/16—Devices for withdrawing samples in the liquid or fluent state with provision for intake at several levels
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
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- Metallurgy (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
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- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
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- Pathology (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Immunology (AREA)
- Thermal Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Manufacturing & Machinery (AREA)
- Heat Treatment Of Articles (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
The invention discloses a casting method of an LC1 valve casting, and belongs to the technical field of valve part casting. The method comprises the steps of mould manufacturing, modeling, paint brushing, mould closing, smelting, casting, mould opening, sand cleaning, casting head cutting, polishing, heat treatment, shot blasting and inspection; smelting by adopting EAF (electric arc furnace) and LF (refining furnace) method processes; the chemical components are specially controlled, the carbon content is specially controlled to be less than or equal to 0.20wt%, the manganese content is specially controlled to be 0.60-0.70wt%, the phosphorus content is specially controlled to be less than or equal to 0.025wt%, the sulfur content is specially controlled to be less than or equal to 0.015wt%, the silicon content is controlled according to standard values, the molybdenum content is specially controlled to be 0.55-0.65wt%, and the nickel content is controlled to be 0.30-0.40 wt%; the quenching and tempering heat treatment method is adopted, and the low-temperature impact toughness is higher than that of the normalizing and tempering heat treatment method. By adopting the casting method, the low-temperature impact toughness of the LC1 valve casting is greatly improved, and the low-temperature impact value at minus 52 ℃ is required to be more than or equal to 27J.
Description
Technical Field
The invention relates to a casting method of an LC1 valve casting, and belongs to the technical field of valve part casting.
Background
The LC1 casting is used as a carbon-molybdenum steel valve part and has wide application in the construction of petrochemical equipment. The manufacturing standard ASTMA352/A352M-2021 prescribes that the content of molybdenum element in the LC1 casting is 0.45-0.65wt%, and the molybdenum element can refine the crystal grains of the steel, improve the hardenability of the steel and effectively inhibit the growth of austenite crystal grains at high temperature. Thus, the standard specifies that the minimum of two samples and the minimum average of three tests are 18J and the minimum of a single sample is 14J for LC1 castings at a test temperature of-59 ℃. In addition, the standard specifies that LC1 castings can be supplied in either a normalizing plus tempering treatment or a liquid quenching plus tempering condition, with a minimum tempering temperature of 590 ℃.
However, as petrochemical plant construction areas expand, particularly in alpine regions, the application environment of LC1 castings becomes more severe. At present, many petrochemical devices are built in high and cold areas, and valves are required to work normally in a low-temperature environment of-52 ℃.
In order to cope with the requirements under the extreme environmental conditions and also to avoid catastrophic accidents caused by brittle fracture of the LC1 casting in the extreme environment of-52 ℃, users put forward higher low-temperature impact value requirements on the LC1 casting, namely the low-temperature impact value at-52 ℃ is more than or equal to 27J. This requirement is far beyond the level specified by the astm a352/a352M-2021 standard, and thus it is difficult for current domestic foundries to meet this high requirement. The domestic foundry can not basically meet the requirement of more than or equal to 27J, generally only 20J, and the current thought mainly surrounds the heat treatment method, but the effect is poor.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a casting method of an LC1 valve casting, which can improve the purity of molten steel, remarkably reduce the quantity and the size of inclusions in the steel, and further improve the impact toughness, particularly the low-temperature impact toughness, of materials.
The technical problems to be solved by the invention are realized by adopting the following technical scheme: the casting method mainly comprises the steps of mould manufacturing, modeling, paint brushing, mould closing, smelting, casting, mould opening, sand cleaning, casting head cutting, polishing, heat treatment, shot blasting and inspection.
The smelting adopts an EAF (electric arc furnace) +LF (refining furnace) method flow to smelt, improves the purity of molten steel, obviously reduces the quantity and the size of inclusions in the steel, and further improves the impact toughness of materials, especially the low-temperature impact toughness.
The method comprises the steps of adopting a spectrometer to rapidly detect chemical components before casting, and specially controlling the chemical components to improve the low-temperature impact toughness of LC1, wherein the chemical components of the LC1 valve casting are designed according to the mass percentage: the carbon content is controlled to be less than or equal to 0.20wt%, the manganese content is controlled to be 0.60-0.70wt%, the phosphorus content is controlled to be less than or equal to 0.025wt%, the sulfur content is controlled to be less than or equal to 0.015wt%, the silicon content is controlled according to standard value, and the molybdenum content is controlled to be 0.55-0.65wt%. Besides special control of elements specified by the standard, the nickel content is controlled in the range of 0.30-0.40wt%, and the nickel element can obviously improve the plasticity and toughness of steel, especially the low-temperature impact toughness, while improving the strength.
The quenching and tempering heat treatment method is adopted, and the low-temperature impact toughness is higher than that of the normalizing and tempering heat treatment method.
The quenching heat treatment method comprises the following steps: the furnace charging temperature of the casting is less than or equal to 200 ℃, and the temperature rising rate is 120 ℃/h. When the temperature is raised to 750+/-10 ℃, preserving heat for at least 1h, and then raising the temperature to 900+/-10 ℃. The heat preservation time at 900+/-10 ℃ is calculated according to the maximum wall thickness of the casting, and the heat preservation time is 25.4mm/h, and the minimum time is 2h. The cooling mode is water cooling, the time from the complete opening of the furnace door to the complete immersion of the casting in water is not more than 60 seconds, the water temperature before quenching is not more than 35 ℃, and the water temperature of a water tank in the quenching process cannot be more than 50 ℃.
The tempering heat treatment method comprises the following steps: and tempering immediately after quenching, wherein the tempering temperature is 650+/-10 ℃ and the heating rate is 120 ℃/h. The heat preservation time at 650+/-10 ℃ is calculated according to the maximum wall thickness of the casting, the heat preservation time is 25.4mm/h, the minimum time is 3h, and the cooling mode is air cooling.
As a preferable example, before the pouring step, sampling molten steel after smelting by adopting a sampling tool and detecting chemical components of a sampled molten steel sample by adopting a spectrometer;
the utility model discloses a sample frock, including the fixed frock of outside and inside rotation frock, fixed frock includes guide cylinder and carries a kind spherical crown body, guide cylinder bottom and the internal chamber intercommunication of carrying a kind spherical crown, it is equipped with the delivery port to carry a kind spherical crown body side, it includes dwang and a kind spherical crown body to rotate the frock, the dwang rotates and sets up inside the guide cylinder, the dwang bottom is connected with a kind spherical crown body, a kind spherical crown body side is provided with the water inlet, just a kind spherical crown body rotates and sets up in carrying a kind spherical crown body inside, the outer spherical surface of a kind spherical crown body and the interior spherical laminating of carrying a kind spherical crown body.
As a preferable example, the area of the outer spherical surface of the sampling spherical cap body is larger than the area of the water outlet on the side surface of the sample loading spherical cap body.
As a preferable example, the guide cylinder is sequentially provided with a plurality of sample loading spherical crown bodies from top to bottom, and the rotating rod is sequentially and correspondingly provided with a plurality of sample loading spherical crown bodies from top to bottom.
As a preferred example, the sample loading platform is further provided with a plurality of hemispherical sample grooves, and the diameter of the hemispherical sample grooves is equal to that of the sample loading spherical crown body.
Compared with the prior art, the invention has the beneficial effects that:
(1) Smelting is carried out by adopting an EAF (electric arc furnace) +LF (refining furnace) method flow, thereby improving the purity of molten steel, obviously reducing the quantity and the size of inclusions in the steel, and further improving the impact toughness, especially the low-temperature impact toughness, of the material;
(2) In order to improve the low-temperature impact toughness of LC1, besides the special control of the contents of carbon, manganese, phosphorus, sulfur and molybdenum, the nickel content is controlled within the range of 0.30-0.40wt%, and the nickel element can obviously improve the plasticity and toughness of steel, especially the low-temperature impact toughness, while improving the strength;
(3) The quenching and tempering heat treatment method is adopted, so that the low-temperature impact toughness is higher than that of the normalizing and tempering heat treatment method;
(4) By adopting the casting method, the low-temperature impact toughness of LC1 is greatly improved, and the low-temperature impact value at minus 52 ℃ is required to be more than or equal to 27J;
(5) By adopting the special-designed molten steel sampling tool provided by the invention, the molten steel of the valve casting before casting after smelting can be sampled in a layered manner, and the components are detected by a spectrometer, so that the chemical components of the LC1 casting can be controlled more accurately.
Drawings
FIG. 1 is a flow chart of a heat treatment process of the casting method of the present invention;
FIG. 2 is a schematic diagram of a front view structure of a molten steel sampling tool before casting in an embodiment of the invention;
FIG. 3 is a schematic diagram showing a cross-sectional structure of a molten steel sampling tool before casting in an embodiment of the invention;
FIG. 4 is a schematic diagram of a cross-sectional structure of a molten steel sampling tool after sampling before casting in an embodiment of the invention;
FIG. 5 is a schematic structural view of a pre-cast molten steel sampling tool and a sample carrier in an embodiment of the invention.
In the figure: 1. sampling tool; 101. a guide cylinder; 102. a rotating lever; 103. a sample-carrying spherical cap body; 104. sampling the spherical cap body; 105. a water inlet; 106. a water outlet; 107. rotating the bracelet; 108. a clamping ring; 109. a clamping groove; 2. a sample loading table; 201. a sample tank; 202. and a limit protrusion.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and are not to be construed as limiting the present invention.
The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific methods and materials, but one of ordinary skill in the art will recognize the application of other methods and/or the use of other materials.
The invention provides a casting method of an LC1 valve casting, which mainly comprises the steps of mould manufacturing, modeling, paint brushing, box closing, smelting, pouring, box opening, sand cleaning, casting head cutting, polishing, heat treatment, shot blasting and inspection.
Specifically, the mould is manufactured:
and (3) mold design: the structure of the mold is designed according to the shape and size of the LC1 valve casting product.
And (3) manufacturing a mould: a mold for casting LC1 valve castings is made using metal or other suitable materials.
Modeling:
preparing a die: and installing the manufactured mold on a mold table.
And (5) die filling: and placing the core material in the mold to ensure that the core material is matched with the mold.
And (3) brushing paint:
and (3) coating: a layer of paint is applied to the core surface to increase the separation between the mold and the casting.
Closing:
and (3) die assembly: the two parts of the mold are closed to form a sealed cavity for pouring molten steel.
Smelting:
preparing metal: LC1 carbon molybdenum steel to be cast is prepared, and the carbon molybdenum steel is heated to a liquid state, typically by smelting.
Pouring:
casting metal: molten carbon molybdenum steel was poured into the mold, filling the entire cavity.
Opening the box:
opening the mold: and opening the die assembly, and taking out the solidified casting.
Sand cleaning:
cleaning residual sand: residual sand is removed from the casting surface and mold.
Cutting a casting head:
cutting a gate and a riser: and cutting off a gate and a riser connected with the casting to complete the shape of the final casting.
Polishing:
grinding the surface: and (3) polishing the casting, removing the surface roughness and improving the surface quality.
And (3) heat treatment:
the heat treatment method comprises the following steps: the castings are heat treated as necessary to alter their properties and structure.
Blasting:
surface treatment: the surface is cleaned by using shot blasting equipment, so that the surface quality and corrosion resistance are improved.
And (3) checking:
and (3) quality inspection: the quality inspection of castings, including the detection of size, shape and material properties.
Smelting: the EAF (electric arc furnace) +LF (refining furnace) method is adopted for smelting, so that the purity of molten steel is improved, the number and the size of inclusions in the steel are obviously reduced, and the impact toughness, particularly the low-temperature impact toughness, of the material is further improved.
The chemical components are rapidly detected by a spectrometer before casting, and the chemical components are specially controlled in order to improve the low-temperature impact toughness of LC 1:
carbon content: the standard rule is less than or equal to 0.25 weight percent, the special control is less than or equal to 0.20 weight percent, the carbon element can improve the hardness and strength of the steel, but the plasticity and toughness of the steel can be reduced, and the carbon content is controlled to the lower limit value.
Manganese content: the standard prescribes 0.50-0.80wt%, and the manganese element is specially controlled at 0.60-0.70wt% to raise the hardenability of steel, but the austenite grains are easy to be coarse at high temperature, the low temperature impact toughness of steel is lowered, and the manganese content is controlled at the intermediate value.
Phosphorus content: the standard rule is less than or equal to 0.040 weight percent, the special control is less than or equal to 0.025 weight percent, the brittleness of the steel is increased by phosphorus, and the phosphorus content is required to be strictly controlled.
Sulfur content: the standard rule is less than or equal to 0.045wt percent, the special control is less than or equal to 0.015wt percent, the brittleness of the steel is increased by the sulfur element, and the sulfur content is required to be strictly controlled.
Silicon content: standard regulation is less than or equal to 0.060wt percent, and the control is carried out according to standard values.
Molybdenum content: the standard prescribes 0.45-0.65wt%, and the molybdenum element is specially controlled at 0.55-0.65wt%, so that the crystal grains of the steel can be thinned, the hardenability of the steel is improved, the growth of austenite crystal grains can be effectively inhibited at high temperature, and the molybdenum content is controlled at an upper limit value.
Besides special control of elements specified by the standard, the nickel content is controlled in the range of 0.30-0.40wt%, and the nickel element can obviously improve the plasticity and toughness of steel, especially the low-temperature impact toughness, while improving the strength.
Referring to fig. 1, the low-temperature impact toughness is higher by the quenching and tempering heat treatment method than by the normalizing and tempering heat treatment method.
The quenching heat treatment method comprises the following steps: the furnace charging temperature of the casting is less than or equal to 200 ℃, and the temperature rising rate is 120 ℃/h. When the temperature is raised to 750+/-10 ℃, preserving heat for at least 1h, and then raising the temperature to 900+/-10 ℃. The heat preservation time at 900+/-10 ℃ is calculated according to the maximum wall thickness of the casting, and the heat preservation time is 25.4mm/h, and the minimum time is 2h. The cooling mode is water cooling, the time from the complete opening of the furnace door to the complete immersion of the casting in water is not more than 60 seconds, the water temperature before quenching is not more than 35 ℃, and the water temperature of a water tank in the quenching process cannot be more than 50 ℃.
The tempering heat treatment method comprises the following steps: and tempering immediately after quenching, wherein the tempering temperature is 650+/-10 ℃ and the heating rate is 120 ℃/h. The heat preservation time at 650+/-10 ℃ is calculated according to the maximum wall thickness of the casting, the heat preservation time is 25.4mm/h, the minimum time is 3h, and the cooling mode is air cooling.
Examples:
1) Smelting by adopting an EAF (electric arc furnace) +LF (refining furnace) method flow;
2) The chemical composition within the LC1 valve castings was controlled as shown in table 1 below:
3) And (3) heat treatment:
the quenching heat treatment method comprises the following steps: the furnace charging temperature of the casting is 150 ℃, and the temperature rising rate is 120 ℃/h. When the temperature is raised to 750 ℃, the temperature is kept for 1.5 hours, and then the temperature is raised to 900 ℃. Preserving heat for 3h at 900 ℃, cooling by water cooling, wherein the time from the complete opening of the furnace door to the complete immersion of the casting in water is 40 seconds, the water temperature before quenching is 25 ℃, and the water temperature in a water tank in the quenching process is 40 ℃.
The tempering heat treatment method comprises the following steps: and tempering immediately after quenching, wherein the tempering temperature is 650 ℃, and the heating rate is 120 ℃/h. Preserving heat for 4.5h at 650 ℃, and cooling by air cooling.
4) Example test results, as shown in table 2 below:
5) Conclusion:
according to the contents in tables 1 and 2, by adopting the casting method of the LC1 valve casting provided by the invention, the purity of molten steel can be improved, the number and the size of inclusions in the steel are obviously reduced, the impact toughness, particularly the low-temperature impact toughness, of a material is further improved, the low-temperature impact toughness of LC1 is greatly improved, and the special requirement that the low-temperature impact value at-52 ℃ is more than or equal to 27J is met.
Referring to fig. 2-4, in order to ensure the accuracy of the content of each chemical component in the LC1 carbon molybdenum steel before the casting step, sampling detection and component content analysis control are required for the molten steel, in the embodiment of the present invention, a specially designed layered sampling tool 1 is used to sample the molten steel after smelting, and a spectrometer is used to detect the chemical components of the sampled molten steel sample.
Specifically, sample frock 1 includes outside fixed frock and inside rotation frock, fixed frock and rotation frock all adopt nickel plating's carbon steel to make, fixed frock includes guide cylinder 101 and year appearance spherical crown body 103, outside at guide cylinder 101 is provided with clamping ring 108, clamping groove 109 has been seted up on the clamping ring 108, the whole of the interior cylindrical cavity of clamp centre gripping sample frock of being convenient for 1, the bottom opening of guide cylinder 101 and the inner chamber intercommunication of year appearance spherical crown body 103, the side of year appearance spherical crown body 103 is equipped with delivery port 106, because the surface tension of molten steel is great, tiny hole is difficult to flow in the molten steel, consequently, diameter with the delivery port 106 setting is 20mm at least, the rotation frock includes dwang 102 and takes a sample spherical crown body 104, dwang 102 top fixedly connected with rotates bracelet 107, dwang 102 rotates and sets up in guide cylinder 101 inside, the dwang 102 bottom is connected with a sample spherical crown body 104, take a sample spherical crown body 104 side is provided with water inlet 105, and take a sample spherical crown body 104 rotates and sets up in a sample spherical crown body 103 inside, the spherical crown body's of being equipped with a sample spherical crown body's 103, the surface of ball 104 and the inner sphere 103 laminating for the molten steel of carrying the appearance spherical crown body 103, the surface of carrying the spherical crown body's surface 103 is guaranteed to be in order to take a sample spherical crown body's the inside the spherical crown body's 106, the area of taking a sample spherical crown body's 106 is big in order to take a sample spherical crown 106.
In order to realize layered sampling of molten steel and enable obtained detection data to be more accurate, a plurality of sampling spherical crown bodies 103 are sequentially arranged on the guide cylinder 101 of the sampling tool 1 from top to bottom, at least three sampling spherical crown bodies 104 are sequentially and correspondingly arranged on the rotating rod 102 from top to bottom.
Referring to fig. 5, the sampled molten steel is stored in the inner cavities of the sample loading spherical crown body 103 and the sample loading spherical crown body 104, in order to facilitate the detection of the chemical components of the molten steel by the spectrometer, the invention also designs a sample bearing table 2 matched with the sampling tool 1, a plurality of hemispherical sample grooves 201 are arranged on the sample bearing table 2, the diameter of the hemispherical sample grooves 201 is equal to that of the sample loading spherical crown body 103, the sample bearing table 2 is made of precoated sand, limiting protrusions 202 are formed between every two sample grooves 201, and the limiting protrusions 202 are just matched with grooves between every two sample loading spherical crown bodies 103 to prevent the sample bearing table from moving forwards and backwards.
The layered molten steel sampling tool 1 provided by the invention can be used for sampling the molten steel LC1 before casting after melting and detecting the components of the molten steel on the sample bearing table 2 by using the spectrometer, so that the effective and accurate control of each chemical component in the molten steel in the casting production process can be ensured.
In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, unless specifically defined otherwise.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (3)
1. A method of casting an LC1 valve casting comprising the steps of: mould manufacturing, modeling, paint brushing, mould closing, smelting, casting, mould opening, sand cleaning, casting head cutting, polishing, heat treatment, shot blasting and inspection; the method is characterized in that in the smelting process, smelting is carried out by adopting an electric arc furnace and a refining furnace method flow;
in the smelting process, the chemical components of the LC1 valve casting are designed as follows in percentage by mass: the carbon content is controlled to be less than or equal to 0.20wt%, the manganese content is controlled to be 0.60-0.70wt%, the phosphorus content is controlled to be less than or equal to 0.025wt%, the sulfur content is controlled to be less than or equal to 0.015wt%, the silicon content is controlled according to standard values, the molybdenum content is controlled to be 0.613-0.65wt%, and the nickel content is controlled to be 0.30-0.40 wt%;
before the pouring step, sampling molten steel after smelting by adopting a sampling tool, and detecting chemical components of a sampled molten steel sample by adopting a spectrometer;
the sampling tool comprises an external fixing tool and an internal rotating tool, the fixing tool comprises a guide cylinder and a sample loading spherical crown body, the bottom of the guide cylinder is communicated with the inner cavity of the sample loading spherical crown body, the side surface of the sample loading spherical crown body is provided with a water outlet, the rotating tool comprises a rotating rod and a sampling spherical crown body, the rotating rod is rotationally arranged in the guide cylinder, the bottom of the rotating rod is connected with the sampling spherical crown body, the side surface of the sampling spherical crown body is provided with a water inlet, the sampling spherical crown body is rotationally arranged in the sample loading spherical crown body, and the outer spherical surface of the sampling spherical crown body is attached to the inner spherical surface of the sample loading spherical crown body;
the area of the outer spherical surface of the sampling spherical cap body is larger than the area of the water outlet on the side surface of the sample carrying spherical cap body;
the guide cylinder is sequentially provided with a plurality of sampling spherical crown bodies from top to bottom, and the rotating rod is sequentially and correspondingly provided with a plurality of sampling spherical crown bodies from top to bottom;
the sample loading platform is provided with a plurality of hemispherical sample grooves, and the diameter of each hemispherical sample groove is equal to that of the sample loading spherical crown body;
the heat treatment adopts a quenching heat treatment method and a tempering heat treatment method;
the quenching heat treatment method comprises the following steps:
the charging temperature of the LC1 valve casting is less than or equal to 200 ℃, the heating rate is 120 ℃/h, and when the temperature is increased to 750+/-10 ℃, the temperature is kept for at least 1h;
then heating to 900+/-10 ℃, wherein the heat preservation time is 25.4mm/h, and when the heat preservation time calculated according to the maximum wall thickness of the casting is less than 2h, the heat preservation time is 2h;
the cooling mode is water cooling; the water temperature of a water tank before quenching is less than or equal to 35 ℃;
the tempering heat treatment method comprises the following steps:
and tempering immediately after quenching, wherein the tempering temperature is 650+/-10 ℃, the heating rate is 120 ℃/h, the heat preservation time at 650+/-10 ℃ is 25.4mm/h, and when the heat preservation time calculated according to the maximum wall thickness of the casting is lower than 3h, the heat preservation time is 3h, and the cooling mode is air cooling.
2. A method of casting an LC1 valve casting according to claim 1, wherein the pool water temperature during the quenching heat treatment process is not greater than 50 ℃.
3. The method of casting LC1 valve castings according to claim 1, wherein the time from when the furnace door is fully opened to when the LC1 valve castings are fully immersed in water during the quenching heat treatment method is not more than 60 seconds.
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| CN111850380A (en) * | 2020-07-29 | 2020-10-30 | 南平市建阳区湛卢精密制造有限公司 | Low-temperature carbon steel valve casting material and manufacturing process thereof |
| CN112553413A (en) * | 2020-11-20 | 2021-03-26 | 二重（德阳）重型装备有限公司 | Planet carrier, casting material and heat treatment process thereof |
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| WO2023165614A1 (en) * | 2022-03-04 | 2023-09-07 | 马鞍山钢铁股份有限公司 | Long-service-life high-toughness corrosion-resistant steel for subsea christmas tree valve and heat treatment method and production method for long-service-life high-toughness corrosion-resistant steel for subsea christmas tree valve |
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| CN106001439B (en) * | 2016-06-06 | 2019-01-15 | 湖北万鑫精密铸锻股份有限公司 | A kind of monoblock cast bucket |
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| CN111850380A (en) * | 2020-07-29 | 2020-10-30 | 南平市建阳区湛卢精密制造有限公司 | Low-temperature carbon steel valve casting material and manufacturing process thereof |
| CN112553413A (en) * | 2020-11-20 | 2021-03-26 | 二重（德阳）重型装备有限公司 | Planet carrier, casting material and heat treatment process thereof |
| WO2023165614A1 (en) * | 2022-03-04 | 2023-09-07 | 马鞍山钢铁股份有限公司 | Long-service-life high-toughness corrosion-resistant steel for subsea christmas tree valve and heat treatment method and production method for long-service-life high-toughness corrosion-resistant steel for subsea christmas tree valve |
| CN114959192A (en) * | 2022-06-09 | 2022-08-30 | 安徽应流集团霍山铸造有限公司 | Heat treatment process method for improving low-temperature impact toughness of low-carbon low-alloy steel |
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